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Re: Horn loaded Corona Build [message #91914 is a reply to message #91874] Tue, 19 May 2020 15:43 Go to previous messageGo to next message
dawiipgh is currently offline  dawiipgh
Messages: 6
Registered: May 2020
Esquire

I have a question based on interchanging components.

If I start the build with the base model components (Eminence) and later upgrade to the higher end components (JBL and B&C), will the existing cabinet and crossovers still work?

  • Will the screw holes for the woofer and mounting location for the compression driver be the same?

  • Are the resistors and capacitors the same on the crossover board?

  • And most importantly, will I be able to install the needed upgrades through the existing openings for the woofer and waveguide?
If anyone has gone through an upgrade, I'd love to hear about it!

Thanks,

dawiipgh
Re: Horn loaded Corona Build [message #91915 is a reply to message #91914] Tue, 19 May 2020 15:59 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17778
Registered: January 2001
Illuminati (33rd Degree)

The woofer and tweeter are direct replacements, and they can be exchanged through the front of the baffle. The cabinet stays the same.

There are some crossover changed required, but they are inexpensive and pretty easy to do. Some resistor values are different for the DE250 because it has slightly higher voltage sensitivity than the PSD2002. You can see the components used for each option in the "Notes" section of the crossover document.

Here are some of my thoughts about the upgrades available:
Re: Horn loaded Corona Build [message #91940 is a reply to message #91915] Sun, 24 May 2020 08:45 Go to previous messageGo to next message
dawiipgh is currently offline  dawiipgh
Messages: 6
Registered: May 2020
Esquire
Hi Wayne,

I've been searching through the FAQ, threads and other website locations. I found the performance data of the 4 Pi speakers:
https://www.pispeakers.com/Measurements/fourPi.html

Your note at the bottom states that "Measurements were taken at a distance of 10 feet from the baffle and drive voltage was 8.62vrms. This is equivalent to 2.83v/M and 1W/1M values since average impedance is 8Ω."

Interpreting the graph, it looks like the 4 Pi speakers clock in around 98-99 dB/W/1M. This is incredibly efficient!

I was considering purchasing an integrated Amp from Yamaha to power the 4 Pi speakers.
https://usa.yamaha.com/products/audio_visual/hifi_components/a-s301/
60 watts x 2 channels into 8 ohms (20-20,000 Hz) at 0.019% THD

This should be able to provide ample power to drive these speakers. A quick calculation taking into account 99 dB/W/1M efficient speakers and 60 Watts of Power at 8 feet listening distance in a room with speakers positioned ~2 ft from the walls gives a an estimated SPL of 115 dB. This is more than enough.

My question comes to what plate amp to use for the flanking sub. I believe I read that the driver for the sub is the Eminence Lab 12 in a large ported box tuned to 20Hz https://www.eminence.com/speakers/speaker-detail/?model=LAB_12

I was considering the Bash 300S or the Bash 500S.
https://www.parts-express.com/bash-300s-digital-subwoofer-plate-amplifier-300w-rms--300-750
or
https://www.parts-express.com/bash-500s-digital-subwoofer-plate-amplifier-500w-rms--300-752

I can't seem to find an amp that the second order roll off that is discussed here.

Any plate amp suggestions or guidance is much appreciated.

Thanks!

dawiipgh
Re: Horn loaded Corona Build [message #91945 is a reply to message #91940] Sun, 24 May 2020 10:59 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 17778
Registered: January 2001
Illuminati (33rd Degree)

If you search here for "flanking sub crossover" you'll find lots of threads where we discuss different crossovers and amps. Some are plate amps and some are separate crossovers and amps. But the truth is, you're right, that most plate amps offer only a fourth-order slope.

One of the exceptions is miniDSP. Not only do they provide stand-alone crossovers but they also offer plate amps. So that makes it really easy - just set it for "100Hz BW2" and you're done. Naturally, the subs need 10dB more gain than the mains too, which can be done either by attenuating the mains or boosting the subs.

Don't make 'em loud enough that you can hear them distinctly - They should be very subtle. You should be able to turn on or off the subs and notice very little difference except for more bass extension. The lower midrange will be smoother too, but that's subtle. So basically, the SPL should be set so the subs aren't noticeable. Each side becomes like a three-way speaker that sounds like a single seamless sound source.
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